I read the procedure in the VNX PG.... SPA & B needs rebooting.
But is there a workaround to go without the reboot ?
there is no workaround to prevent the reboot, but be aware that the SPA and SPB will reboot one at a time.
This does not require downtime for your applications provided you have double attachment and failover software properly configured.
Still it is recommanded to do so during offpeak hours.